Browsing by Author "Chen, Jing-Heng"

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4-Port polarization-independent wavelength-interleaving bidirectional circulator
(2008-01-15)
Hsieh, Po-Jen
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Chen, Jing-Heng
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Hsieh, Hung-Chih
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Jian, Zhi-Cheng
;
Su, Der-Chin
This study develops an alternative type of 4-port polarization-independent wavelength-interleaving bidirectional circulator. In this circulator the even- and odd-channels circulate with opposite handedness regardless of the state of polarization of signals. It has a pair of orthogonal holographic spatial- and polarization modules (HSPMs) and a Lyot-Ohman filter (LOF). Each HSPM has two holographic spatial walk-off polarizers (HSWPs), two glass plates and two half-wave plates. The function of the HSWJP is firstly described. Next, the structures and the operating principles of the HSPM and the LOF are also described. Then, the operating principle and the performance of this circulator are discussed. It has such merits as polarization-independence, compactness, high isolation, lack of polarization mode dispersion and ease of fabrication. (c) 2007 Elsevier B.V. All rights reserved.
62nm CW wavelength-selectable erbium-doped fiber compound-ring laser with stable single-mode output
(2019-12-01)
Yeh, Chien-Hung
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Chang, Yao-Jen
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Lin, Wen-Piao
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Xie, Yue-Ru
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Luo, Chien-Ming
In this demonstration, an erbium-doped fiber (EDF) based laser with stable, wide and wavelength-selectable single-longitudinal-mode (SLM) performances is designed and demonstrated. Here, to achieve SLM oscillation, a compound-ring scheme is constructed in the EDF laser cavity serving as a mode-restriction-filter for densely side-mode suppression. Moreover, the continuous-wave tunability can be scaled from 1520.0 to 1582.0 nm by using the proposed compound-ring scheme and commercial C-band EDF amplifier. In the measurement, the output stability and 3 dB Lorentzian linewidth of each lasing wavelength in the proposed EDF compound-ring laser have also been discussed.
A new type of liquid refractometer
(2008)
Lin, Jiun-You
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Chen, Jing-Heng
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Chen, Kun-Huang
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Su, Der-Chin
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光電工程學系
A new liquid refractometer is proposed based on the phenomenon of total-internal reflection and the technique of heterodyne interferometry. A special designed glass probe is immersed in the tested liquid, and a light beam is guided within this probe due to the total internal reflections. After the light beam is totally reflected at the other end of the probe, it goes back in an anti-parallel direction of the original path. Because of multiple total-internal reflections, the phase difference, which is determined by the heterodyne interferometry between the p- and s-polarizations, is greatly enhanced to result in an accurate refractive index. The feasibility of this method was demonstrated by our experimental results, and a resolution of 5x10(-3) is obtained with our method. This method should, therefore, bear the merits of high accuracy, high stability, and easy operation.
Adaptive and secure VCSEL FSO based on simple dual-polarized architecture for short distance transmission
(2020-09-01)
Yeh, Chien-Hung
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Yang, Yun-Cheng
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Hsu, Tzu-An
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Chen, Yu-Wen
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Chow, Chi-Wai
In this study, using dual-polarized-multiplexing VCSEL based free space optical (FSO) transmission system is demonstrated experimentally. Two orthogonal polarizers (POLs), a beam splitter (BS) and a reflected mirror (M) are applied in the FSO transmitter (Tx) side to combine dual FSO signals into one for data security without code encryption. In the receiver (Rx) side, two blended FSO channels can be decoded adaptively by applying a POL with properly polarization status. Furthermore, when we add two corresponding POLs with orthogonal polarization in the Rx side, the FSO capacity also can double by the presented dual-polarized FSO architecture. Here, the relationships of the detected FSO powers and rotating angle between two POLs are also experimentally discussed.
An alternative method for simultaneously measuring cell parameters of a twisted-nematic liquid crystal cell
(2008)
Chen, Kun-Huang
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Chen, Jing-Heng
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Lin, Jiun-You
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Su, Der-Chin
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Su, Jung-Chieh
A phase-sensitive method is developed to simultaneously measure the cell parameters of a TNLC (twisted-nematic liquid crystal) cell based on Jones calculus and the heterodyne interferometric ellisometry. These cell parameters include the twist angle, the cell gap, and the angle of the entrance LC director. When a circularly polarized heterodyne light beam normally passes through a TNLC cell, the phase difference between the p- and s- polarization of the interference signal can be measured accurately with an analyzer and the heterodyne interferometric ellisometry. The phase difference depends on the azimuth angle of the analyzer and the parameters. By substituting the measured values of the phase differences at three different azimuth angles of the analyzer into the special equations derived with Jones calculus. Hence these three para meters can be esitimated by using a personal computer with numerical analysis technique. Because of its common path optical configuration and its heterodyne interferometric ellisometry, this method has many merits such as high stability against the surrounding vibration, high resolution, and easy operation.
Based on Silicon-micro-ring-resonator and Triple-ring Cavity for Stable and Tunable Erbium Fiber Laser
(2018-01-01)
Hsu, Yung
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Chang, Yuan-Chia
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Yeh, Chien-Hung
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Chow, Chi-Wai
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Chen, Jing-Heng
In this paper, a stable and wavelength-switchable erbium-doped fiber (EDF) laser by utilizing the silicon-micro-ring-resonator (SMRR) and multiple-fiber-ring (MFR) scheme is demonstrated. Here, three optical couplers (CPs) can construct the passive MFR in the proposed and achieve single-longitudinal-mode (SLM) output simultaneously. The SMRR is used inside a fiber cavity as mode restrict element for wavelength-tuning. By properly adjusting the polarization controllers (PCs), the output wavelength can be tuned in a wavelength range of 1544.35 to 1564.10nm with a similar to 2.0 nm tuning step. Hence, the proposed EDF laser can reach the characteristics of SLM output, 35 kHz output linewidth, and optical single-to-noise ratios (OSNRs) of > 54.9 dB. In addition, the output stabilities of the power and wavelength in the proposed EDF laser are also discussed.
Collimation testing and calibration using a heterodyne Moire method
(2014-11-01)
Chang, Wei-Yao
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Hsu, Ken Y.
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Chen, Kun-Huang
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Chen, Jing-Heng
;
光電工程學系
This study proposes a simple, rapid, and highly accurate method to achieve the collimation testing and calibration of laser light beams. By applying a relative constant velocity to two gratings, every pixel of a CMOS camera can receive a series of heterodyne moire signals. Based on the least squares sine fitting algorithm, the phase of the optimized sinusoidal wave can be obtained. Consequently, the phase slope along the direction perpendicular to the grating lines can be estimated and then used to judge the degree of collimation. Furthermore, by measuring only two phase slopes at two positions of the collimating lens, the calibration of the light beam collimation can also be achieved. The experiment validated the proposed method, and the positioning error of the light beam collimation was approximately 7 mu m. (C) 2014 Elsevier Ltd. All rights reserved.
Corneal surface reconstruction by using heterodyne moire method
(2013)
Chang, Wei-Yao
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Chen, Kun-Huang
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Chen, Der-Chin
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Tseng, Jung-Kai
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Chen, Shyan-Tarng
In this paper, we propose a simple method for reconstructing the corneal surface profile by using the Talbot effect, projection moire method, and heterodyne interferometry. A linear grating is obliquely illuminated by an expanding collimated light, and a self-image of this grating can be generated and projected on the corneal surface. The deformed grating fringes are imaged on the second grating to form the moire fringes. If the first grating is moved with a constant velocity along the grating plane, a series of sampling points of the sinusoidal wave which behave like the heterodyne interferometric signal can be recorded by a CMOS camera. The phase distribution of the corneal surface then can be obtained with the IEEE 1241 least-square sine fitting algorithm and 2D phase unwrapping. Finally, the corneal surface profile can be reconstructed by substituting the phase distribution into special derived equation. This method provides the advantages of a simple optical setup, ease of operation, high stability, and high resolution.
Full-field refractive index measurement with simultaneous phase-shift interferometry
(2014)
Chu, Yen-Chang
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Chang, Wei-Yao
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Chen, Kun-Huang
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Chen, Jing-Heng
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Tsai, Bo-Chung
Using the phenomenon of total internal reflection and a beam splitting device, a technique of simultaneous phase-shift interferometry is proposed for measuring the full-field refractive index. Because this method applies a beam splitting device that mimics the characteristics of beam splitting and phase modulation, four interferemetric images of various phase distributions can be simultaneously captured. Therefore, this setup can avoid errors caused by non-simultaneous capturing of images and offers the benefits of high stability, ease of operation, and real-time measurement. Furthermore, using the phenomenon of total internal reflection, the phase difference between p- and s-polarized light varies considerably with the refractive index of a tested specimen. This can substantially increase the measurement resolution. The feasibility of this method is verified using an experiment, and the measurement resolution can be higher than 3.65 x 10(-4) RIU. (C) 2014 Elsevier GmbH. All rights reserved.
Generating Radially and Azimuthally Polarized Beams by Using a Pair of Lateral Displacement Beamsplitters
(2016-09-01)
Han, Chien-Yuan
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Wei, Zhi-Hao
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Hsu, Yung
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Chen, Kun-Huang
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Yeh, Chien-Hung
This paper proposes a modified polarization converter for generating radially and azimuthally polarized beams. Based on a Mach-Zehnder-like interferometric structure, the device consists of a pair of lateral displacement beamsplitters (LDBs) and two half-wave plates that manipulate the states of polarization of incident linearly polarized light. Through the coherent superposition of two orthogonal Hermite-Gaussian modes in the far field, radially and azimuthally polarized beams can be obtained simultaneously. A prototype was assembled to demonstrate the feasibility of the design. The proposed design has the advantage of having a simple, symmetric, compact, and robust structure. In addition, the introduction of LDBs substantially reduces the cost of this device. Moreover, the design can be applied to a broadband pulsed laser with considerable potential in high-power applications.
Heterodyne moire interferometry for measuring corneal surface profile
(2014-03-01)
Chang, Wei-Yao
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Chen, Kun-Huang
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Chen, Der-Chin
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Tseng, Jung-Kai
;
Chen, Shyan-Tarng
This study proposes an accurate method for reconstructing the corneal surface profile. By applying a constant velocity to the projection grating along the grating plane, a series of sampling points of the sinusoidal wave, which behaves in the manner of heterodyne interferometric signals, can be recorded using a CMOS camera. The phase distribution of the moire fringes can then be obtained using the IEEE 1241 least-square sine fitting algorithm and two-dimensional (2D) phase unwrapping. Finally, the corneal surface profile can be reconstructed by substituting the phase distribution into a specially derived equation. To validate the proposed method, the corneal surface of a pig eyeball was measured. The measurement resolution was approximately 3.5 mu m. Because of the introduction of the Talbot effect, the projection moire method, and heterodyne interferometry, this approach provides the advantages of a simple optical setup, ease of operation, high stability, and high resolution. (C) 2013 Elsevier Ltd. All rights reserved.
Heterodyne moire surface profilometry
(2014-02-10)
Chang, Wei-Yao
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Hsu, Fan-Hsi
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Chen, Kun-Huang
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Chen, Jing-Heng
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Hsu, Ken Y.
In this study, a novel moire fringe analysis technique is proposed for measuring the surface profile of an object. After applying a relative displacement between two gratings at a constant velocity, every pixel of CMOS camera can capture a heterodyne moire signal. The precise phase distribution of the moire fringes can be extracted using a one-dimensional fast Fourier transform (FFT) analysis on every pixel, simultaneously filtering the harmonic noise of the moire fringes. Finally, the surface profile of the tested objected can be generated by substituting the phase distribution into the relevant equation. The findings demonstrate the feasibility of this measuring method, and the measurement error was approximately 4.3 mu m. The proposed method exhibits the merits of the Talbot effect, projection moire method, FFT analysis, and heterodyne interferometry. (C) 2014 Optical Society of America
Optimized design of multiport optical circulator
(2014)
Hsu, Fan-Hsi
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Chen, Jing-Heng
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Chen, Kun-Huang
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Yeh, Chien-Hung
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Hsu, Ken Y.
This research proposes a practical multiport optical circulator design by using polarizing beam splitter cubes as spatial walk-off polarizers. The use of Porro prisms for directing light requires fewer components and improves space-efficiency. Therefore, a high performance device can be produced at a reduced cost. A six-port optical circulator prototype was fabricated to show the feasibility of the proposed design. The insertion losses range between 0.52 and 1.05 dB, the isolations range between 26.20 and 45.13 dB, and the return losses are 27.72 dB. The benefits of this design\'s simple and symmetrical structure include costefficiency, simple fabrication processes, polarization-independence, the resolve of polarization-mode dispersion issues, and high performance. Additionally, the number of ports can be increased easily. (c) 2014 Elsevier GmbH. All rights reserved.
Prism-hologram-prism sandwiched recording method for polarization-selective substrate-mode volume holograms with a large diffraction angle
(2018-08-06)
Hsu, Fan-Hsi
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Han, Chien-Yuan
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Chen, Kun-Huang
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Hsu, Ken-Yuh
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Chen, Jing-Heng
We propose a prism-hologram-prism sandwiched recording method for the fabrication of polarization-selective substrate-mode volume holograms with a large diffraction angle. In fabrication, the C-RT20 photopolymer is sandwiched between two 45 degrees-90 degrees-45 degrees prisms and the interference fringes can be easily recorded in the recording material. The experimental results are in good agreement with the theoretical predictions. The proposed method features of a reflection-type recording setup for a transmission element and belongs to a technique of longer-wavelength construction for shorter-wavelength reconstruction. In addition, the method is much easier than the traditional recording method of two incident beam interference and has application potential in holographic photonics. (c) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Reconstruction of surface profile by using heterodyne moire method
(2012-11-01)
Chang, Wei-Yao
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Hsu, Fan-Hsi
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Chen, Kun-Huang
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Chen, Jing-Heng
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Hsieh, Hung-Chih
Based on the projection moire method and heterodyne interferometry, this study proposes an alternative method for reconstructing the surface profile of an object. Obliquely illuminating a linear grating with an expanding collimated light, a self-image of this grating can be generated and projected on the surface of the tested object. The grating fringes distorted by the surface profile are imaged on the reference grating to form the moire fringes. These moire fringes are then captured by a CMOS camera. If the projection grating moves with a constant velocity along the grating plane, each pixel of the CMOS camera records a series of sampling points of the sinusoidal wave. These sinusoidal waves behave like heterodyne interferometric signals. Hence, the accurate and stable phase distribution of the tested object surface can be obtained using the IEEE 1241 least-squares sine fitting algorithm and 20 phase unwrapping. Substituting the phase values into the derived equation, the surface profile of the tested object can be reconstructed. The experiments in this study verified the feasibility of this method, showing a measurement resolution of approximately 1.9 mu m. The proposed measurement method has the merits of both the projection moire method and the heterodyne interferometry. (C) 2012 Elsevier B.V. All rights reserved.
Silicon-Micro-Ring Resonator-Based Erbium Fiber Laser With Single-Longitudinal-Mode Oscillation
(2018-06-01)
Yeh, Chien-Hung
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Cheng, Hao-Yun
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Chang, Yuan-Chia
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Chow, Chi-Wai
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Chen, Jing-Heng
In this paper, we propose and experimentally illustrate a wavelength-switchable erbium-doped fiber (EDF) dual-ring (DR) laser with stable single-longitudinal-mode (SLM) oscillation. In the experiment, a silicon-micro-ring-resonator (SiMRR) is applied in the proposed DR cavity for tuning different output wavelengths, when the birefringence loss is adjusted correctly. To compress the densely multilongitudinal-mode oscillations, the DR scheme together with a 2-m unpumped EDF-based saturable absorber is acted as the mode filter. The DR also can produce self-injection loop for an SLM operation. The wavelength tunability is between 1532.61 to 1557.98 nm and the measured 3-dB output linewidth is similar to 22.5 kHz. Moreover, the output stabilizations of the proposed SiMRR-based EDF DR laser are also analyzed and discussed.
Smart architecture for stable multipoint fiber Bragg grating sensor system
(2017-12-01)
Yeh, Chien-Hung
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Tsai, Ning
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Zhuang, Yuan-Hong
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Huang, Tzu-Jung
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Chow, Chi-Wai
In this work, we propose and investigate an intelligent fiber Bragg grating (FBG)-based sensor system in which the proposed stabilized and wavelength-tunable single-longitudinal-mode erbium-doped fiber laser can improve the sensing accuracy of wavelength-division-multiplexing multiple FBG sensors in a longer fiber transmission distance. Moreover, we also demonstrate the proposed sensor architecture to enhance the FBG capacity for sensing strain and temperature, simultaneously.
Stabilized and tunable single-longitudinal-mode erbium fiber laser employing ytterbium-doped fiber based interference filter
(2017-02)
Yeh, Chien-Hung
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Tsai, Ning
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Zhuang, Yuan-Hong
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Chow, Chi-Wai
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Chen, Jing-Heng
In this demonstration, to achieve stabilized and wavelength-selectable single-longitudinal-mode (SLM) erbium doped fiber (EDF) laser, a short length of ytterbium-doped fiber (YDF) is utilized to serve as a spatial multi mode interference (MMI) inside a fiber cavity for suppressing multi-longitudinal-mode (MLM) significantly. In the measurement, the output powers and optical signal to noise ratios (OSNRs) of proposed EDF ring laser are measured between 9.85 and 5.71 dBm; and 38.03 and 47.95 dB, respectively, in the tuning range of 1530.0-1560.0 nm. In addition, the output SLM and stability performance are also analyzed and discussed experimentally.
Stable and Tunable Single-Longitudinal-Mode Erbium-Doped Fiber Triple-Ring Laser With Power-Equalized Output
(2016-04-01)
Yeh, Chien-Hung
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Chen, Jhih-Yu
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Chen, Hone-Zhang
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Chen, Jing-Heng
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Chow, Chi-Wai
In this demonstration, we propose and investigate a stable and tunable single-longitudinal-mode (SLM) erbium-doped fiber (EDF) ring laser structure. Here, in order to achieve the SLM output, the "eye-type" triple-ring scheme is designed in this EDF laser to suppress the densely spaced longitudinal modes. In the measurement, the output power and optical-signal-to-noise ratio (OSNR) are between 8.35 and 8.92 dBm and 33.2 and 35.7 dB, respectively, in the wavelength range of 1530 to 1560 nm. The proposed EDF laser architecture not only has free tuning step but provides stabilized and flattened output power spectrum as well.
Stable and wavelength-tunable RSOA- and SOA-based fiber ring laser
(2014-06-01)
Yeh, Chien-Hung
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Sung, Jiun-Yu
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Yang, Ling-Gang
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Chow, Chi-Wai
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Chen, Jing-Heng
In this work, we propose and experimentally investigate a wavelength-tunable fiber ring laser architecture by using the reflective semiconductor optical amplifier (RSOA) and semiconductor optical amplifier (SOA). Here, the wavelength tuning range from 1538.03 to 1561.91 nm can be obtained. The measured output power and optical signal to noise ratio (OSNRs) of the proposed fiber laser are between -0.8 and -2.5 dBm and 59.1 and 61.0 dB/0.06 nm, respectively. The power and wavelength stabilities of the proposed laser are also studied. In addition, the proposed laser can be directly modulated at 2.5 Gbit/s quadrature phase shift keying-orthogonal frequency-division multiplexing (QPSK-OFDM) signal and 20-50 km single-mode fiber (SMF) transmissions are achieved within the forward error correction (FEC) limit without dispersion compensation. It could be a cost-effective and promising candidate for the standard-reach and extended-reach wavelength division multiplexed passive optical network (WDM-PON). (C) 2014 Elsevier Inc. All rights reserved.